Impact of changes in governance for anticoagulant rodenticide use on non-target exposure in red foxes (Vulpes vulpes)

Abstract

Wildlife is at risk of exposure to rodenticides used in pest management. An industry-led stewardship scheme introduced new rules on use and sale of products across the UK in 2016, with the aim of reducing this risk. To determine if the scheme had achieved this, exposure to second generation anticoagulant rodenticides (SGARs) was measured in foxes. Liver samples from 406 foxes collected between 2011 and 2022 were analysed and the percentage presence and concentrations of SGARs, where present, from pre-stewardship and post-stewardship samples were compared. There was no statistically significant change in the percentage of foxes exposed to bromadiolone, difenacoum or summed SGAR residues after the introduction of stewardship. The percentage of foxes exposed to brodifacoum increased significantly post-stewardship, from 18% to 43%. There were no significant changes of either summed or individual SGAR concentrations post-stewardship.

These findings suggest that the industry-led stewardship scheme has not yet had the intended impact of reducing SGAR exposure in non-target wildlife, and they highlight a substantial increase in foxes encountering brodifacoum, together with weak statistical evidence of an increase in the percentage of foxes exposed to multiple SGARs.